Need high density liquid

MikeConnelley

Hello:

We are looking for a high density liquid to replace mercury due to mercury's toxicity. We currently user mercury to float the primary mirror of the telescope that I work for. Due to the way that our mirror was made, we need a non-toxic liquid with a density of at least 6.5 g/cc that is liquid below 0C, and preferably liquid below -10C. The closest thing that I have found so far is Galinstan, but I'm not sure that it's dense enough to work.

Cheers
Mike